Photoelectric keyboard



April 21, 1970 T. M. LENO 3,507,996

PHOTOELEGTRIC KEYBOARD Filed Jan. 29, 1968 2 SheetsShee' 1 INVENTOR THEODORE M. LENO WNSZ Mm'i? ATTORNEY A ril 21, 1970 T. M. LENO 3,507,99

PHOTOELECTR IC KEYBOARD Filed Jan. 29, 1968 2 Sheets-Sheet 2 United States Patent ice 3,507,996 PHOTOELECTRIC KEYBOARD Theodore M. Leno, Arlington Heights, Ill., assignor to Teletype Corporation, Skokie, 111., a corporation of Delaware Filed Jan. 29, 1968, Ser. No. 701,378 Int. Cl. H041 15/20 US. Cl. 178-17 6 Claims ABSTRACT OF THE DISCLOSURE A keyboard comprises a plurality of similar character generating units mounted side by side between a light source and an array of photocells. The keyboard includes a frame and a keytop mounted for reeiprocatory movement on the frame. A driving connection angularly moves a coded shutter on the frame during an initial portion of the movement of the keytop and for thereafter enables uncoupling of the shutter from the keytop so that the shutter returns to its initial position independently of the keytop.

BACKGROUND OF THE INVENTION Teletypewriter and other encoding keyboards often present an unususal touc to persons familiar with the touch of ordinary manual or electric typewriters. This difference in touch, which often renders the operation of teletypewriters by ordinary typists diflicult and prone to error, is caused in part by the requirement of most teletypewriter keyboards that one key be completely restored to an unactuated position before another key can be depressed. The keys of ordinary typewriters, on the other hand, can be actuated regardless of whether a previously depressed key has been released. This characteristic, known as accumulation in the keyboard art, is highly desirable in teletypewriter keyboards intended for operation by persons familiar with the operation of ordinary typewriters.

SUMMARY OF THE INVENTION This invention comprises an encoding keyboard having improved touch characteristics due in part to a provision for accumulation of keys. In the preferred embodiment the keyboard includes keytops mounted for reciprocatory movement in the usual manner and encoding members mounted for angular movement by the keytops during a portion of the keytop movement and for independent return movement after a predetermined amount of keytop travel.

DESCRIPTION OF THE DRAWINGS A more complete understanding of the invention may be had by referring to the following detailed description when taken in conjunction with the drawings wherein:

FIGURE 1 is a front view of a keyboard encoding mechanism employing the present invention in which certain parts have been broken away and in which certain other parts have been omitted more clearly to illustrate certain features of the invention;

FIGURE 2 is a sectional view taken along the line 22 in FIGURE 1 in the direction of the arrows in which certain parts have been broken away more clearly to illustrate certain features of the invention;

FIGURE 3 is a right side view of one of the individual encoding units employed in the mechanism shown in FIGURE 1;

FIGURE 3A is a view similar to FIGURE 3 showing the component parts of the mechanism in the position they occupy at a different stage in the operation of the device;

3,507,996 Patented Apr. 21, 1970 DETAILED DESCRIPTION Referring now to the drawings, wherein like reference numerals designate like parts throughout the several views, and referring particularly to FIGURE 1 there is shown a keyboard encoding mechanism of the photoelectric variety. The mechanism is enclosed in a shell or housing 11 that is comprised of a pair of side plates 12 and 13, a rear plate 14, a bottom plate 15 and a front plate 16 which extends upwardly and rearwardly of the device in the form of a top plate 17 that has a plurality of keytop holes 18 formed through it. The housing 11 may be formed from plastic or some other similar material and may be dispensed with entirely depending upon the particular use to which the keyboard encoding mechanism is to be put.

Mounted within the shell 11 is a basket 21 which forms a frame or support structure for the keyboard encoding mechanism. The basket 21 is comprised of a rear plate 24, a bottom plate 25 and a front plate 26 which is identical to the rear plate 24 but which is not shown in FIG- URE 1.

Mounted within the basket 21 is an encoding assembly 30 comprised of a plurality of individual encoding units 31 that are mounted side by side in the nature of the slices of bread in a loaf. Positioned at the left hand end (FIGURE 1) of the encoding assembly 30 is a light generating assembly 35. The light generating assembly 35 is comprised of a printed circuit board 36 having a plurality of light bulbs 37 mounted on it (only one of which is shown) and also having appropriate printed circuitry (not shown) for providing electrical current to the light bulbs 37. The light bulbs 37 extend rightwardly (FIGURE 1) from the printed circuit board 36 and are substantially enclosed in a gasket 38 formed from rubber or the like. Positioned between the gasket 38 and the left hand most (FIGURE 1) individual encoding unit 31 of the encoding assembly 30 is a plate 39 having a plurality of holes formed through it in alignment with the light bulbs 37 through which light passes from the light generating unit 35 into the encoding assembly 32. It should be understood that the light generating assembly 35 need not be comprised of a plurality of light bulbs and may instead be comprised of a single light source together with suitable lenses, etc., for directing light through the plate 39 and into the encoding assembly 30.

Positioned at the right hand end (FIGURE 1) of the encoding assembly 30 is a light detecting assembly 45 which, like the light generating assembly 35, includes a printed circuit board 4-6, a gasket 48 and plate 49 having a plurality of holes each in alignment with one of the light bulbs 37 formed through it. The light detecting assembly is different from the light generating assembly in that light sensitive devices 47 (only one of which is shown in FIGURE 1), rather than light bulbs, are mounted on the printed circuit board 46 in alignment with the holes in the plate 49. Like the printed circuit board 36, the printed circuit board 46 has appropriate printed circuitry (not shown) formed upon it for sampling the outputs of the photosensitive devices 47 and for directing such outputs to a remote location whereat they may be utilized in any of several well known manners.

The individual encoding units 31 of the encoding assembly 30 each include a keylever 55 and each of the keylevers 55 has a keytop 56 attached to its upper most end which extends through one of the holes 18 in the top plate 17 of the shell 11. The keylevers 55 are mounted in the individual encoding units 31 for vertical reciprocatory movement with respect to the basket 21 in the usual manner. A portion of the movement of the keylevers is opposed by a keylever return mechanism 60 comprised of a bar 61 which extends across the entire width of the keyboard and which is supported in engagement with a pair of rods 62 and 63 that extend between the rear plate 24 and the front plate 26 of the basket 21 by a pair of springs 64 and 65. The springs 64 and 65 are connected between the bar 61 and a pair of rods 66 and 67 which, like the rods 62 and 63, extend between the plates 24 and 26. A more complete understanding of the keylever return mechanism 60 may be had by referring to the copending application of A. A. Hagstrom, Ser. No. 603,638, filed Dec. 21, 1966.

Referring now to FIGURE 2 there is shown a partial left side view of one of the individual encoding units 31. Each of the individual encoding units 31 has a square keyway 70 similar to the keyway 70 shown in FIGURE 2 formed through it and a square rod 71 extends through all of the keyways 70 of the encoding units 31. The units 31 also each have a similar keyway 72 formed through them at a point indicated in the drawing by the arrow 73 and a square rod 74 similar to the rod 71 extends through all of the keyways 72. The rods 71 and 74 each terminate in threaded ends similar to the threaded end 75 of the rod 74 shown in FIGURE 2 and threaded fasteners similar to the fastener 76 are engaged with each of the ends 75 of each of the rods 71 and 74 to join the encoding assembly 30 into a unitary structure. Both the threaded ends 75 and the threaded fasteners 76 are located in circular notches similar to the notch 77 shown in FIGURE 2 that are formed in the circuit boards 36 and 46 and the gaskets 38 and 48 respectively so that neither the ends 75 nor the threaded fasteners 76 are visible in FIGURE 1. The encoding assembly 30 is shown in FIGURE 2 supported on a pair of tabs 78 and 79 formed in the rear plate 24 and the front plate 26 of the basket 21 respectively; however, the assembly 30 may be supported in the basket 21 in anysuitable manner.

Referring now to FIGURE 3, one of the individual encoding units 31 is shown in detail, it being understood that the other units are substantially identical to the one shown. Each of the units 31 includes a frame 80 which is formed from brass, hard plastic or the like and which serves as a support for all of the components of the individual encoding unit. A keylever 55 is mounted on each of the frames 80 and is guided for reciprocatory movement with respect thereto against and with the action of a spring 81 that is attached to the frame 80 by a rivet 82 by a pair of pins 83 and 84 which extend from the right hand leg (FIGURE 3) of the keylever 55 through slots 85 and 86 formed through the frame 80 and by a pin 87 which extends from the left hand leg of the keylever 55 (FIGURE 3) through a slot 88 in the frame 80. The keylevers 55 each have a keytop 56 mounted on them which may be positioned as shown in FIGURE 3 or which may be positioned anywhere along the horizontally extending arm of the keylever 55 depending upon the position the keytop 56 is to occupy with respect to the remaining keytops of the keyboard.

A rocking lever 90 is mounted within a shallow cutaway area 91 of the frame 80 and is supported on a pin 92 for oscillatory motion with respect to the frame 80. The rocking lever 90 is driven by the keylever 55 through the pin 87 which extends through a slot 93 in the rocking lever 90 and which is secured with respect to the lever 90 by a snap ring 94. A finger 95 is mounted on the rocking lever 90 and is supported for oscillating movement with respect thereto by a pin 96. The finger 95 is urged to rock counterclockwise about the pin 96 by a torsion spring 97 which extends from a hole 98 in the rocking lever 90 around the pin 96 and under the finger 95. Further counterclockwise motion of the pin 95 from the position shown in FIGURE 3 is prevented by a tab 99 formed integrally with the finger and extending over the rocking lever 90. The finger 95 is positioned within a cutaway area 100 in the frame 80 so that as the keylever 55 is reciprocated upwardly and downwardly the finger 95 travels in an arcuate path about the pin 92.

Mounted within a cutaway area that is approximately as deep as the area 91 and that is not so deep as the area 100 is a shutter 106. The shutter 106 is supported for oscillatory movement with respect to the frame 80 by a pin 107 extending through the shutter 106 and the frame 80. In the particular embodiment shown the pin 107 extends through the entire encoding assembly 30, through the light generating assembly 35 and through the light detecting assembly 45 and terminates in threaded portions upon which a pair of threaded fasteners 108 (shown in FIGURE 1) are mounted. If desired, however, the pin 107 can be comprised of a plurality of separate pins formed integrally with or otherwise attached to each of the frames 80' for supporting the shutters 106 of the individual frames and not extending into other frames 80.

A plurality of code bit generating holes 110 and a universal hole 111 are formed through each of the frames 80 and are positioned in rings about the pin 10 7 so that light normally passes from the light generating assembly 35 to the light receiving assembly 45 through a plurality of straight channels each including the same hole in each of the frames 80. The shutters 106 are provided with a plurality of light blocking tabs 112 which are adapted to be selectively broken away from the shutters 106 to provide a predetermined pattern of light blocking tabs positioned to cover predetermined ones of the holes 110 upon rocking motion of a particular one of the shutters 106 thereby blocking predetermined ones of the light conducting channels. Each of the shutters 106 also has a universal hole blocking tab 113- which is positioned to block the universal hole 111 of its frame 80' upon rocking motion of the shutter. A pin 114 extends from the tab 113 under the finger 95 through a hole 115 formed completely through the frame 80. The shutter 106 is urged to rock clockwise about the pin 107 by a spring 116 connected between the shutter and the frame 80 and is maintained in the position shown in the drawing by a pin 117 which may be covered with rubber or some other sound absorbing material if desired.

The cutaway areas 91, 100 and 105 in the frames 80 provide for the mounting of all of the components of the encoding units 31 within the major outlines of their respective frames 80. This construction assures that a seal is formed between each pair of adjacent individual encoding units 31 in the encoding assembly 30 and thus is particularly useful in the construction of photoelectric keyboards wherein light conducting channels must be sealed against the entry of oil, dirt, etc., if reliable operation is to be guaranteed.

OPERATION When ever the keytop 56 of one of the individual encoding units 31 is depressed by an operator the keylever 55 attached to that keytop 56 moves downwardly initially against the action of the spring 81 attached to its respective frame 80 and subsequently against the action of both the spring -81 and the keylever return bar 61. Downward movement of the keylever 55 causes the pin 87 to move downwardly which in turn causes the rocking lever 90 to pivot clockwise about the pin 92. This causes the finger 95 to move in a clockwise direction in an arc about the pin 92. Since the finger 95 is positioned over the pin 114 that is attached to the universal hole blocking tab 113 of the shutter 106 of the frame 80 of the depressed keytop 56, this causes the shutter to rock counterclockwise about the pin 107 against the action of the spring 116. This action continues until the various component parts of the mechanism reach the position shown in FIGURE 3A whereat, because of the diverging paths followed by the finger 95 and the pin 114 due to their arcuate paths of travel, the finger 95 and the pin 114 are about to become disengaged one from the other. During this time the tabs 112 on the shutter 106 move into a blocking relationship with their respective holes 110 and then move past the blocking relationship into the position shown in FIGURE 3A. It should be noted that the universal hole blocking tab 113 is circumferentially wider than the tabs 110 and accordingly the universal hole 111 is blocked by the universal hole blocking tab 113 when the parts are in the position shown in FIG- URE 3A.

When the keytop 56 is depressed slightly past the position shown in FIGURE 3, the finger 95 and the pin 114 disengage themselves from each other and the shutter 106 snaps back to the position shown in FIGURE 3A under the action of the spring 116. It is important to realize that this action takes place regardless of whether the keytop is held depressed or is released since the shutter 106 is completely uncoupled from the keylever 55 and all of the parts connected to it.

During the return movement of the shutter 106 the shutter passes through the position shown in FIGURE 3B. In that position the tabs 112 on the shutter 106 completely block their respective holes 110. However, the universal hole blocking tab 113 is offset slightly with respect to the universal hole 111 and, accordingly, when the shutter is in the position shown in FIGURE 3B the universal hole 111 is partially uncovered.

The output of the photosensitive device 47 aligned with the universal holes 111 through the frames 80 is constantly monitored so that whenever the photosensitive device aligned with the universal holes 111 is completely dark, that is, whenever light passing through the universal hole channel is blocked by one of the uni versal hole blocking tabs 113, the circuitry connected to the photosensitive devices 47 is primed to receive a character. Then, whenever a predetermined amount of light is sensed by the photosensitive device 47 aligned with the universal holes 111, which amount of light is indicative of the opening of one of the holes by the amount shown in FIGURE 3B, the outputs of all of the photosensitive devices 47 aligned with the channels comprised of the holes 110 is sampled. At this point the channels extending through the encoding assembly 30 aligned with certain of those photosensitive devices 47 are blocked by tabs 112 whereas certain other channels are open since the tabs 112 aligned with those holes have been broken away. Therefore the detection of light by certain of the photocells aligned with the unblocked holes 110 and the absence of the detection of light by the remaining photocells aligned with the blocked holes 110 is indicative of the character represented by the particular one of the keytops that was depressed and may be utilized by appropriate circuitry to generate a character.

Anytime after the shutter 106 corresponding to the depressed key 56 has been uncoupled from its keylever 55 the keytop 56 may be released. Such release causes the keylever 55 to move upwardly under the action of the spring 81 and the keylever return bar 61 thereby pivoting the rocking lever 90 counterclockwise about the pin 92 until the rocking lever 90 is in the position shown in FIG- URE 3. During this return movement the finger 95 engages the inside of the pin 114. However, since the finger 95 is pivotally supported on the lever 90 the finger 915 merely pivots clockwise about the lever 90 against the action of the spring 97 until it clears the pin 114 and then snaps into the position shown in FIGURE 3 under the action of the spring 97. This returns the mechanism to the condition shown in FIGURE 3. It should be understood that since the generation of a character follows the disengagement of the finger 95 and the pin 114 and since upon disengagement the shutter 106 immediately returns to the position shown in FIGURE 3, it is not necessary to release a previously depressed keytop 56 before depressing another keytop 56 and thereby generat 6 ing another character. Thus, the mechanism shown in FIGURES 3, 3A and 3B provides for the accumulation of keys in an encoding keyboard.

Although only one embodiment of the invention is shown in the drawings and described in the foregoing specification it will be understood that the specific embodiment is illustrative only, being adapted for modification and rearrangement, and substitution of parts and elements.

1 claim: 1. In a device for generating electrically coded output signals each of which is an analog function of light coded by an encoding shutter cycled in response to operation of a key mounted in a keyboard for reciprocation between a start stroke position and an end stroke position, the combination comprising:

means for angularly moving the shutter in a nonencoding first phase of said cycle in an arcuate path between a first station and a second station;

means for coupling said key to said shutter during an initial portion of movement from said start stroke position to said end stroke position to move said shutter from said first station to said second station;

means for spontaneously returning said shutter in said path to said first station in an encoding second phase of said cycle whenever said shutter reaches said second station; and

means for initiating encoding as said shutter returns to said first station.

2. A combination according to claim 1 wherein said coupling means is arranged for releasing said shutter from said key when said shutter reaches said second position.

3. A combination according to claim 2 further characterized by a third station disposed between said first and said second stations at which said initiating means becomes effective as said shutter returns to said first station from said second station and following release of said shutter.

4. A combination according to claim 1 wherein said coupling means comprises an interposer having a shutter engaging projection, said projection and said shutter arranged for movement in opposite angular direction as said shutter is moved by said key from said first to said second station, said projection proportioned for disengaging from said shutter as said key moves toward its end stroke position following movement of said shutter to its second station.

5. A combination according to claim 4 characterized by spring means for returning said shutter to said first station and arranged for tensioning in response to move ment of said key in an initial part of its movement toward said end stroke position to efiect rapid shutter return immediately upon uncoupling of said key and said shutter.

6. A combination according to claim 4 further characterized by a light source;

a signal generator including light detection means,

aligned with said source,

said shutter disposed between said light source and said light detecting means for encoding light passed therebetween, and

means for preventing signal generation as said shutter moves from said first station to said second station.

References Cited UNITED STATES PATENTS 3,334,237 8/1967 Dodsworth et al. 19798 X 3,104,388 9/ 1963 Balenger. 3,369,643 2/ 1968 Avgerinos et al.

THOMAS A. ROBINSON, Primary Examiner US. Cl. X.R. 197-98 

